| 摘要 |
The present invention can easily realize an optical fiber and an optical transmission line that can propagate a light in a single mode while lowering a macro-bending loss against a small-diameter bending. An optical fiber 1 according to the present invention includes a first cladding region 3 having a refractive index lower than a refractive index of a core region 2 on outer circumference of the core region 2. Sub-medium regions 5a to 5f, 6a to 6f are arranged in multilayer in the first cladding region 3, which have a refractive index lower than a refractive index of a main-medium region of the first cladding region 3. The sub-medium regions 5a to 5f having a circular shape with a lateral cross section of a diameter d1 is arranged in an inner cladding area 3a of the first cladding region 3, and the sub-medium regions 6a to 6f having a circular shape with a lateral cross section of a diameter d2 (>d1) is arranged in an outer cladding area 3b of the first cladding region 3. |
